1. Field of the Invention
The present invention relates to a waterproof push switch.
2. Description of the Related Art
In terms of waterproof push switches, for example, Japanese Patent Laid Open Publication No. 2005-203315 describes a push switch comprising a push button 103, a board 110, a dome (switch) 111, a back cover (stopper) 113 and a tubular case 101, as shown in FIG. 6.
At the edge of an opening in the case 101, an annular rib 105 is provided, which is bent towards the interior of the opening, and a groove 106 is provided between this annular rib 105 and the internal circumference of the case.
A flange 108 is provided on the outer circumference of the push button 103, and a protrusion 107 is provided on the flange 108, which fits into the groove 106.
When the push button 103 is arranged in the case, the protrusion 107 on the push button 103 fits into the groove 106 in the case. The board 110 is inserted by way of the lower opening of the case 101. This board 110 is disposed in contact with the bottom of the flange 108 on the push button 103, and is fixed in place by the back cover 113.
With the push switch in FIG. 6, if a drop of water adheres to the top of the push switch, it is possible that, via the groove 106, the drop of water will pass between the flange 108 and the board 110, and ingress to the interior of the push button 103. Furthermore, if a drop of water adheres to the bottom of the push switch, it is possible that the drop of water will move along the inner face of the case 101, pass between the flange 108 on the push button 103 and the board 110, and ingress to the interior of the push button 103.
Consequently, with the push switch in FIG. 6, in order to keep the interior of the push button 103 waterproof, it is necessary to apply potting materials (fillers) 109, 114 in two places: on the top of the annular rib 105 that is provided on the case, and at the bottom opening of the case. This requires numerous potting material application steps, making the production characteristics extremely poor.
Furthermore, because the curing times for potting materials are generally very long, requiring approximately one day, and because a drying space must be provided, there was a demand for a reduction in potting material application steps.